Abstract: An adult continues acquiring new lexical entries in everyday life. Brain networks and processes at play when producing newly learnt words might be similar to well-known words, yet some processes are bound to be slower. Here, we compared the neural dynamics of producing newly acquired words with those of well-known frequent words, both qualitatively and quantitatively, using event-related potentials (ERPs) associated to high-density microstate analyses. ERPs revealed several temporal windows with differences in waveform amplitudes, which correspond to enhanced duration of similar microstates for newly acquired words compared to well-known words. The time-periods of these ERP modulations converged to suggest that both lexical processes and word form encoding are slowed down for words that have been learned recently, but that the same brain processes are implemented as for well-known words.